Sharpness is a term used to describe the clarity of detail in an image. Two fundamental factors that contribute to the perceived sharpness of an image are resolution and acutance. Resolution describes the ability of an image capturing device to resolve detail in the object that is being imaged. An image capturing device may include individual components, such as a lens and displaying components that contribute to the resolution of an image. In addition to the components, the environment in which the image is captured can also affect the resolution of the image.
Acutance describes how quickly image information transitions at an edge of an object within the image. An image with high acutance exhibits sharp transitions and clearly-defined borders. An image with low acutance exhibits soft transitions and a lack of clearly-defined borders. Acutance depends on both the quality of the lens of the image capturing device and the post-processing of the captured image. Acutance is typically the only aspect of sharpness that can be adjusted after an image is captured.
Image sharpening is a tool for emphasizing texture and directing viewer focus to an object in an image. Digital camera sensors and lenses oftentimes blur an image to some degree, and this blurring may require correction to enhance the clarity of the image. Image sharpening software sharpens an image by applying a sharpening mask. The use of layered sharpening masks provides a high degree of flexibility in sharpening. Once a layer is created, a sharpening mask can be applied, which sharpens the layer. Acutance can be enhanced during image sharpening.